The present invention relates to a device for remote control or operation of an equipment used in relation to pipes in which a fluid circulates. The operation is performed through the circulation of a flow of fluid which is lower than the working flow rates.
In the field of oil drilling, it is often necessary to remotely operate tools located in the wellbore.
Operating such tools requires high energies.
According to the prior art, an annular piston having two faces and a throttling device comprising a needle-flow bean with a variable flow section are used. One face of this piston is subjected to the pressure forces prevailing on one side of the throttling device, the other face being subjected to the pressure forces on the other side of the throttling device.
The flow bean is generally borne by the piston and the needle is fastened in relation to a duct containing the assembly and within which the piston can move to perform the desired operating function. The piston comprises return means which maintain it in a rest position corresponding to a relatively large flow section of the throttling device, leading to a low pressure drop for the working flow rates.
To operate the equipment, the rate of flow is increased, which raises the pressure drop on either side of the throttling device, and the piston therefore tends to move by acting against the return means. During this motion, the flow bean enters more and more the throttling device, hence a higher increase in the pressure drop providing the power necessary for operating the equipment.
The prior art can be illustrated by French patent 2,575,793.
Such a device lacks precision as far as the threshold flow rate bringing about the activating of the operating is concerned. In fact, the assembly consisting of the piston and the return spring, which must react to or transmit considerable powers, cannot be precisely sensitive to a given threshold flow rate, owing to the frictional stresses for example.
Moreover, the device works through an increase in the flow rate in relation to the working flow rates. But the drilling conditions may forbid such an increase in the flow rate. In fact, the consequent increase in the pressure drops downstream from the device can lead to fracturations in the ground or destabilize the walls of the well, which may challenge the safety of the operation. Besides, a power increase in relation to the power used for drilling is often impossible because the pumping equipment is frequently already run at full power for the drilling operation itself.
French patent 2,641,320 solves the problem of the precision of the threshold flow rate by utilizing a flow bean or a needle borne by the piston, but moving in relation to the piston.
This flow bean or this needle, of a relatively small size in relation to the piston, and equipped with appropriate return means, is precisely sensitive to a flow rate threshold, but the operating still has a major drawback in that it is released by an increase in the flow rate in relation to the working flow rates.
The present invention allows to solve the two problems by using an appropriate needle-flow bean or equivalent system which notably allows to release the operating by using a flow rate threshold less than or equal to the working flow rates, while providing a considerable activation force as necessary for the operating.
According to the prior art, the process which consists in feeding a ball or another sealing device into the fluid circulation pipeline is well-known. The ball falls or is pumped onto a piston comprising a seat. The pipeline being sealed by the ball cooperating with the seat, the pumping can then develop an operating pressure on the piston without requiring a high flow rate. This method still has many drawbacks. In fact, the operation time may be relatively long according to the drilling depth, and the total sealing of the circulation channel requires a complex and delicate system for ejecting the ball after the operating. The failures of such a system can be disastrous for the following operations. The need to have a clear pipeline to let the ball through limits the cases of use, for example it forbids to set a possible downhole motor between the operating device and the surface, and besides no measuring devices are allowed between the device and the surface. These drawbacks are very restrictive, considering the sphere of application which notably concerns directional drilling where such equipments are commonly used.